I. Field of the Invention
This invention relates generally to apparatus for monitoring the volume of liquid being drawn from a supply by way of several discharge conduits, and more particularly to a network flow meter devices interconnected to provide indications of volume rate of flow and total flow from each of the plurality of discharge conduits and the total flow from all such discharge conduits.
II. Discussion of the Prior Art
In fire-fighting systems where water is supplied from a tank on a fire truck, from a municipal hydrant or from another source such as a swimming pool or lake, a so-called mid-ship pump is used to deliver water at high pressure and flow rates to a plurality of discharge conduits on the fire truck. Such a truck may, for example, have a water cannon for delivering water at up to 1,000 gallons per minute, several 13/4 to 21/2 inch diameter attack hoses for directing water onto burning structures at up to 120 gallons per minute and 1 inch diameter hand lines for extinguishing smaller fires and extinguishing "hot-spots" once the fire has been brought under control. Such hand lines may deliver 60 to 90 gallons/minute. In such systems, it is important to know at all times the total amount of water that has been drawn from a tank on the fire truck or from the other water supplies as well as the volume rate of flow and the total flow from each of the separate hoses and lines. This is especially true when a liquid chemical foamant concentrate is being added to the water stream. It is important from the standpoint of optimizing the retardant properties of the water foamant mixture that the precise amounts of foamant concentrate be added to the water stream to maintain a predetermined concentration of the water/foamant mixture.
U.S. Pat. Nos. 5,313,548; 5,232,052; 5,494,112 and RE 35,362 owned by applicants, assignee describe a computer-based system for delivering metered quantities of foam concentrate to a water stream so as to maintain the desired concentration. The system includes a positive displacement pump and a drive motor therefore whose speed can be varied over a wide range to deliver a foam concentrate from a supply tank thereof to a discharge conduit. Associated with the main discharge conduit is a flow meter transducer that feeds information into a microprocessor as to the existing flow rate of liquid through the main discharge conduit and this information is processed to cause the motor to drive the foam concentrate pump at a rate to maintain a preprogrammed foam/water concentration in the stream being delivered out the discharge conduit. Also associated with the microprocessor is a visual display panel which is used to provide a visual indication to the operator of the volume rate of flow and the total flow during a given time period.
When it is recognized that a fire truck may have a plurality of discharge conduits, it is desirable that each individual discharge conduit have its own flow meter transducer and circuitry for displaying the volume rate of flow and total flow out each of the plural discharge conduits. Moreover, it is advantageous that provision be made for computing and displaying the total flow out of all of the plural discharge conduits. This allows a fire fighter on board a fire truck to more readily monitor the volume of water being directed on to a fire and the rate at which an existing supply is being exhausted.
Knowing the volume of water being directed onto the fire in a multi-story building allows a determination of when the weight of the water may be approaching a level where the collapse of a floor may be expected. Firefighters may then be radioed to retreat from the building in advance of any structural failure brought on by the weight of the water delivered. Knowing when the existing supply of water is exhausted will permit the fire-fighters to leave an area before the supply runs dry. Furthermore, knowing the size and strength of a fire-fighter and the flow from the hose he or she is handling, the flow can be adjusted to accommodate that person's capability to hold the hose.